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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division Rationale -Page 5, Permit No. CO-0043648 007A This point will be used to designate any precipitation related overflows from the Vaf[ey Leach Facility which may occur either because the annual precipitation falling on the Valley Leach Facility and the drainage area contributing surface runoff to the leaching facility exceeds the annual evaporation, or because the 10-year, 24-hour storm volume is exceeded. /t is not certain exactly where such discharges might appear around the perimeter of the leach pad, but they would likely enter Arequa Gulch somewhere downstream of the leach facility. Therefore, this point is shown in figure 3 of the permit as being in the vicinity of points OOIA and OO1B. However, it must be noted that any discharge described by point 007A must be sampled immediately after emerging from the leach pad, prior to entering any other receiving stream Based upon the project documentation that is currently available, the discharge poims listed above should be sufftcient to monitor and control all significant point sources of pollutanu that may be discharged to surface waters from process water or combined stormwater/process water. The tx+o main potential sources of such discharges are the Valley Heap Leach Facility and the Arequa Gulch Rock Storage Area. While there are two other major features of the Cresson Project that are potential sources of pollutants -the Cresson Mine Pit and the Iron Clad Rock Storage Area, the project documentation does not indicate that discharges of process water to surface water are likely to occur in these areas. Discharges from these sources are not covered by this permit and would be considered violations of the Colorado Water Quality Control Act and this permit. Also, it is likely that any signhcant amounts of pollutants that might be discharged to groundwater instead of surface water will either be detected by the groundwater monitoring program that CC&V will follow in compliance with authorizations issued by the State Division of Minerals and Geology, or by the monitoring being done at the Carlton Tunnel, which flows underneath the mining district. Should it be discovered that any additional discharges of such a nature are in fact occurring, from any source associated with the Cresson Projecr mining activity, the permit will be re-opened to include appropriate limits and monitoring conditions. 111. RECE/VING STREAM A. ldent~cation, Classflcation and Standards Identification: Discharges to Arequa Gulch, a tributary to Cripple Creek, Segment 2/ of the Upper Arkansas Sub-basin of the Arkansas River Basin. 2. Classification: 7hls stream segment is clnssified for the jollosving uses: Recreation, Class 2,' Aquatic Life, Class / (CoklJ: Agriculture 3. Numeric Standards: Tlie standards which have been assigned in nccordance with the above classficationc can be found in 3.2.0.. Classifications and Numeric Standards for the Arkansas River Basin (5 CCR /002-81, which became effective July 30, 1994. The organic standards which apply to thrs receiving stream are listed in 3.1.0 Basic Standards and Methodoloeies for Surface Water (5 CCR 1002-81, effective January 31, /994. The following numeric standards which have been assigned in accordance with the above classifications will be used to develop effluent limitations. Phvsical and Bia[oeical Standards D.O. = 6.0 mg/1, 7.0 mg/l spawning pH = 6.5 - 9.0 s. u.